It has long been hypothesised that supernovae (SNe) are a
major source of dust in the Universe, an assumption which
has gained support with the discovery that many of the
earliest-formed galaxies are extremely dusty and
IR-luminous, as evidenced by the efficient detection of
their redshifted dust emission at submillimeter wavelengths.
We are now carrying out a sensitive mid-IR Survey for
Evolution of Emission from Dust in SNe (SEEDS, PI: M.\
Barlow) to address the extent to which they produce dust,
and whether they are a primary source of dust in the
Universe. We present {\em Spitzer} observations of young,
nearby SNe, including 1999bw, 2002hh, 2004dh, and 2004et.
Implications for dust formation versus emission from
pre-existing circumstellar dust are discussed.